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Questions tagged [circuit-analysis]

Circuit (Network) analysis is the process of finding the voltages across, and the currents through, every component in the network.

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Appoximation of a transient response of a more complex circuit

I have a "complicated" circuit that I want to approximate as a simple harmonic oscillator. More info below. I have a parallel LRC circuit, with some extra input and output load resistors and coupling ...
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Q: Finding the current through the capacitor

Having a hard time trying to find the current through the capacitor I don't know what method to use. simulate this circuit – Schematic created using CircuitLab This is how far I have gotten: ...
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Nodal Analysis - solving 2 variables with 3 equations

There are three conditions: before the switch is closed (opened) while the switch is closed (closed) after the switch is closed (opened) I think I need to solve them sequentially, because the system ...
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608 views

Diode circuit analysis with two diodes in series

simulate this circuit – Schematic created using CircuitLab In the above schematic the CVD model is being used, with a voltage drop of 0.6 V, for all three diodes. The input voltage sweeps from -...
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201 views

Linear vs. Audio Taper for RC Network

I'm building a distortion pedal and I was wondering which tapers to use for which potentiometers in the tone control section. I normally design my own circuits, but I'm going by someone else's ...
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36 views

Switched circuit analysis - getting rid of “glue” equations

I have the following circuit: simulate this circuit – Schematic created using CircuitLab I would like to derive 3 differential equations, describing it, since it has 3 dynamic components [Csh, ...
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47 views

How to go about finding the transfer function of a non-linear circuit?

Note: The concept of Transfer Function is only defined for linear time invariant systems. Nonlinear system models rather stick to time domain descriptions as nonlinear differential equations rather ...
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74 views

Second Order Circuit, Sadiku's Fundamentals of Electric Circuits

I would like some help with Sadiku's exercise about second order circuits. I did'nt understand why the solution says that V (0) = -30 V. Also, I did not understand why the capacitor's voltage (Vc) ...
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55 views

Series BJT transistors with bases connected through a resistor

For an assignment I was given a problem which consists of two BJT transistors, a PNP and an NPN, in series with their bases tied together. simulate this circuit – Schematic created using ...
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52 views

Finding Current in Parallel RLC Circuit with 2 voltage sources?

I've spent sometime learning about step responses for series/parallel RLC circuits, but this problem takes things a step further, since C seems to be in parallel with a series combination of RL and a ...
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51 views

Determining the output resistance of a BJT amplifier

I'm given the following amplifier: (all the transistors have the same characteristics; Early effect is neglected) In order to calculate \$R_{out}\$, we replace the circuit with its small-signal ...
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103 views

RL Circuit Analysis with 2 sources, how to find current of resistor?

I've been tackling some problems related to natural and step responses for RL & RC circuits, but I think I've hit a major roadblock for this RL circuit. I'm trying to find the time constant and ...
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40 views

Parallel MOSFET Circuit Analysis

I'm solving part b of this question I started with the assumption that both MOSFETs were in saturation mode to simplify calculations, I then solved for the circuit, tested the assumption using vds, ...
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55 views

Resistor for buzzer current consumption limiting calculation

I would like to know how did the circuit designer of the circuit in the image calculated resistor R100 value. My guess is that the 100ohm resistor is to limit the current to ~20mA. I have tried to ...
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108 views

Howcome there is current flowing through the gate of this transistor?

I have a few conceptual questions: If there wasn't Rg (Resistor between gate and drain), would Vin = Vout then? For small signal analysis, current can flow through the gate (AC) if there's a voltage ...
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77 views

How would you find the power balance in this circuit?

I have been having some problems trying to solve the mesh analysis of this circuit to calculate the power balance throughout the circuit. Here is the circuit: simulate this circuit – Schematic ...
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181 views

Power stage for VCR (Voltage Controlled Resistor)

I'm building a VCR (Voltage Controlled Resistor) using the LM13700 component. You can read more details on that here: Floating voltage-controlled resistor with LM13700: How does it work? The problem ...
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61 views

Voltage drops after connecting two batteries in parallel

I have two batteries 12V GEL 130Ah, each charged to 14.4V. After connecting them together in parallel, the voltage drops gradually and equalizes at 12.99V. (I use 10mm^2 short cables to connect them ...
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57 views

Different results for different parallel ports, same circuit. why?

This is my programmer circuit: I decided to try the HCT version of the nor gate (74HCT02) and I also decided to omit the capacitor to the reset. I selected 10K for all resistors except for reset, I ...
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81 views

Question on inductors with initial current

Question: Initially the switch position is aa', 3 H is connected across a 3 A supply and 6 H is connected across 6 A supply. After some time the make before break switch is actuated to the new ...
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34 views

finding two drain currents

below I have the following problem along with the circuit's picture My analysis is as follows: for G and D open \begin{equation} I_{D1}=I_{D2}\hspace{10mm}therefore\hspace{10mm}V_{ov1}=\:V_{ov2} \...
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137 views

Finding the equivelent capacitance of the circuit

Finding the equivelent capacitance of: simulate this circuit – Schematic created using CircuitLab I think that it should be: $$\frac{1}{\frac{1}{C_1}+\frac{1}{C_2}}+\frac{1}{\frac{1}{C_3}+\...
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80 views

How to solve a specific circuit with dependent sources

I am trying to solve this circuit: V1 is the positive side of Vonc and V2 is the positive side of Vint My advisor has us modeling this circuit with respects to some biomedical applications. The ...
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Is it okay to write KVL equations like this (using complex numbers)?

For the circuit shown in the figure, determine the value of \$V_2\$ such that current through \$5\Omega\$ resistance is \$0\$. My attempt: Let current in left loop be \$I_1\$, middle loop be \$I_2\...
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Am I right about measuring current, and power

I have a meter that can measure: current, active power, reactive power and complex power. simulate this circuit – Schematic created using CircuitLab So, when I measure the four things: current,...
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122 views

Solve \$n \times n\$ rectangular grid of resistors for mesh currents

I am modeling a mechanical process by using an electrical analogue. I need to calculate the loop (mesh) currents, then I can see if any mesh current is greater than a predetermined value \$\lambda\$. ...
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Detecting a connection to a distinct circuit with no current return

I hope the title is informative, and that I'm not posting a repeat - part of my problem here I believe is that I don't know the correct terminology to find the answer on the internet as a whole. The ...
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108 views

Can anyone make sense of my electronics instructor's common emitter design?

I think that I need to give a little back story, but I will try to make it short enough as possible. I have a 2 year degree that I describe as half hardware/ half software. What I mean by that is half ...
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99 views

Source voltage and capacitance

Does changing the source voltage (i.e. voltage of the battery) affect how long it takes for a capacitor to charge in a circuit? Am I right in saying that since the capacitor charges until it reaches ...
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187 views

Vpp voltage listed with a division symbol?

I'm reading a spec sheet of an intercom and it lists the electronic call signal with the following notation: 8÷12 Vpp I get that Vpp is Voltage peak-to-peak. ...
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118 views

First-Order Transient Circuit with Capacitor

Consider the following circuit, where the switch is in position A for a long time and moves to position B at time \$t = 0\$. For \$t \geq 0\$, \$v_C(t)\$ and then \$v(t)\$ need to be found. I found \$...
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92 views

Doubt on source free RL circuit

Find \$i\$ and in the circuit . Let \$i(0)=12 A\$ Ans.\$12 e^{-2t}\$ I have worked out the problem(with a little mistake in it)...But I have a few doubts: Doubt: 1)Why is the constant equal ...
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79 views

Problem with Simulation Results VS Tested Results for a signal

For the circuit shown i am having some trouble wondering why my tested signal looks like this (i understand that it could be clipping) but when i measure my circuit in the simulation it is correct? ...
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Li-Po Battery Balance Charging Circuit

I work on a solar tracking project and in this project I have to charge my Li-Po battery to store power and use this power for supplying the system. For this problem, I searched for the li-po battery ...
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226 views

Voltage across capacitor in a electrical circuit (LCC circuit)

My networkanalyses book told me that the voltage across the capacitor C2 is given by: $$\text{U}_{\text{C}_2}\left(t\right)=\text{U}_{\text{in}}\left(t\right)+\text{C}_1\cdot\text{L}\cdot\text{U}_{\...
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261 views

Refrigerator relay has a circuit board?

My fridge stopped cooling and kept hearing a click noise every 2-4 minutes. Researching led me to understand the start relay is nothing more than a PTC resistor that cuts the start winding once ...
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585 views

Heart Rate Monitor Schematic: Somethings Wrong

I am trying to get an analog circuit design for a heart rate monitor and eventually create an output to some graphing tool either on PC or phone/tablet. I have put together the following circuit yet ...
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Determine polarity of feedback circuit

This is an example from Feedback chapter in Fundamentals of Microelectronics by Razavi. As you can see from the picture, the author gives two questions (why?). Could you check if my answers are ...
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a linear system is a bilinear transformation of anyone its circuit elements

I am reading about dissection theorem and the part below is a bit confusing. Could anyone one explain it? Any transfer function of a linear system is a bilinear transformation of anyone its ...
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180 views

Circuit for voltage division and DC shift doesn't work

I've connected the circuit below on a breadboard and tested it in the lab: Components: \$R_{1}=1\,M\Omega,\;R_{2}=40\,k\Omega,\;R_{3}=R_{4}=R_{5}=R_{7}=R_{8}=20\,k\Omega,\;R_{6}=49.9\,k\Omega\...
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299 views

Cross coupled-gm boosting stage

From this paper, a wideband differential LNA is proposed with structure below: The first stage is called "cross coupled- gm boosting stage". I am wondering if there is a mistake here. As seen from ...
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446 views

worst case analysis

I am trying to a worst case/monte carlo analysis of the following circuit. How do I proceed with ? I have Altium and PSPICE(the textual one and not schematic capture). The main components I want to ...
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349 views

how to treat a diode in a transient analysis

Hi, this fig is a model of a circuit, where the cap is representing the gate-to-source capacitance of a hi-side FET in a bridge circuit driving a coil. VD is the intrinsic diode in the FET from Source-...
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621 views

Design for a common source FET Amplifier Circuit

Here's a design question our prof gave us to study for the exam. I'm having trouble putting it together. A common source amplifier is shown. The FET is working in saturation and has gm = 0.5mS, Kn = ...
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185 views

State Equations

Please can you help me in finding the state equations for the circuit below? My problem is the two capacitors. How will we cater for the second capacitor? I only know problems with 1 capacitor and 1 ...
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37 views

Calculation of a current at règime

I have to calculate \$i(t)\$ at règime, by knowing that \$v_s(t)=2\cos(\omega t + \pi/2)\$, \$R=1\Omega\$, and that, at the generator frequency, \$X_c=-1\Omega\$ and \$X_L=1\Omega\$. simulate this ...
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59 views

RC first-grade circuit with op. amplifier

I tried to calculate the voltage \$v_u\$ in this RC circuit, but I got stuck when it comes to calculate \$v_u(\infty)\$ and \$\tau\$. simulate this circuit – Schematic created using CircuitLab ...
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956 views

From RLC prototype to signal flow graph

This simple 3rd order low-pass circuit simulate this circuit – Schematic created using CircuitLab can be described with the following 3 equations: $$-V_1 = \displaystyle \frac{-1}{sC_1} \left(...
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212 views

State Variable Filter analysis

I'm in the process of making my own adaptation of the classic State Variable Filter (SVF) in the analog domain. Reading up on this article. I discovered that they use superposition to get the ...
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938 views

Node Voltage Analysis with independent and dependent voltage sources

simulate this circuit – Schematic created using CircuitLab I'm having trouble solving for the voltage drop across the 80 ohm resistor using the node voltage analysis method. I can get the ...